Bimetallic cluster catalysts

Abstract

A facile synthesis of the precursor, Cp 2 Mo 2 (μ-S) 2 (μ-SH) 2 , to novel heterobimetallic cluster compositions (e.g., Cp 2 Mo 2 Fe 2 (μ-S) 2 (CO) 8 ; Cp 2 Mo 2 Ni 2 (μ 3 -S) 4 (CO) 2 ; Cp 2 Mo 2 Co 2 (μ 3 -S) 2 (μ 4 -S)(CO) 4 ; Cp 2 Mo 2 Fe 2 (μ 3 -S) 4 (CO) 6 and Cp 4 Mo 2 Ni 2 S 4 and the subsequent synthesis and use of the heterobimetallic cluster compositions as highly active and selective catalysts for the hydrogenation of carbon monoxide. Such heterobimetallic cluster catalysts supported on alumina exhibit extraordinary activity and selectivity with respect to the formation of ethane without concommitant formation of C 3 , C 4 and heavier hydrocarbons. The catalysts are contemplated as being useful for syngas conversion even in the presence of several ppm of H 2 S or the like in the feedstream.

We claim: 
     
       1. The heterobimetallic cluster complex selected from the group consisting of Cp 2  Mo 2  Fe 2  (μ-S) 2  (CO) 8  ; Cp 2  Mo 2  Ni 2  (μ 3  -S) 4  (CO) 2  ; Cp 2  Mo 2  Co 2  (μ 3  -S) 2  (μ 4  -S)(CO) 4  ; Cp 2  Mo 2  Fe 2  (μ 3  -S) 4  (CO) 6  and Cp 4  Mo 2  Ni 2  S 4  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       2. The heterobimetallic cluster complex of claim 1; Cp 2  Mo 2  Fe 2  (μ-S) 2  (CO) 8  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       3. The heterobimetallic cluster complex of claim 1; Cp 2  Mo 2  Ni 2  (μ 3  -S) 4  (CO) 2  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       4. The heterobimetallic cluster complex of claim 1; Cp 2  Mo 2  Co 2  (μ 3  -S) 2  (μ 4  -S)(CO) 4  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       5. The heterobimetallic cluster complex of claim 1; Cp 2  Mo 2  Fe 2  (μ 3  -S) 4  (CO) 6  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       6. The heterobimetallic cluster complex of claim 1; Cp 4  Mo 2  Ni 2  S 4  where Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H. 
     
     
       7. The heterobimetallic cluster complex characterized by the formula:   Cp.sub.2 M.sub.2 M.sub.2 'S.sub.x (CO).sub.n     wherein Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H and wherein M is a metal selected from the group consisting of Mo, W and V and wherein M' is a metal selected from the group consisting of Fe, Co and Ni and x and n are integers from about 2 to about 8.   
     
     
       8. A method of synthesizing Cp 2  Mo 2  (μ-S) 2  (μ-SH) 2  consisting of the steps: (a) Chemically reducing the polymeric sulfide (Cp 2  Mo 2  S x ) n  dissolved in an organic solvent with a chemical reducing agent;   (b) quenching the reduction reaction by the addition of water;   (c) stripping the excess solvent and water; and   (d) recovering Cp 2  Mo 2  (μ-S) 2  (μ-S) 2  wherein Cp=η 5  -C 5  H 4  R and R is --CH 3  or --H.   
     
     
       9. A method of claim 8 further comprising the steps of washing the Cp 2  Mo 2  (μ-S) 2  (μ-S) 2  with water and recovering purified Cp 2  Mo 2  (μ-S) 2  (μ-S) 2 . 
     
     
       10. A method of claim 9 wherein said organic solvent is THF and said chemical reducing is LiEt 3  BH. 
     
     
       11. A method of preparing a molybdenum heterobimetallic cluster complex comprising the steps of: (a) reacting Cp 2  Mo 2  (μ-S) 2  (μ-SH) 2  where Cp=η 5  -C 5  H 4  R and R=--CH 3  or --H with a group 8 metal carbonyl selected from the group consisting of Ni(CO) 4 , Co 2  (CO) 8 , Fe 2  (CO) 9  and Cp 2  Ni 2  (CO) 2  ; and   (b) recovering a heterobimetallic cluster composition selected from the group consisting of Cp 2  Mo 2  Ni 2  (μ 3  -S) 4  (CO) 2 , Cp 2  Mo 2  Co 2  (μ 3  -S) 2  (μ 4  -S) (CO) 4 , Cp 2  Mo 2  Fe 2  (μ 3  -S) 4  (CO) 6  and Cp 4  Mo 2  Ni 2  S 4 .   
     
     
       12. A method of claim 11 wherein said group 8 metal carbonyl is Ni(CO) 4  and said heterobimetallic cluster complex is Cp 2  Mo 2  (μ 3  -S) 4  (CO) 2 . 
     
     
       13. A method of claim 11 wherein said group 8 metal carbonyl is Co 2  (CO) 8  and said heterobimetallic cluster complex is Cp 2  Mo 2  Co 2  (μ 3  -S) 2  (μ 4  -S)(CO) 4 . 
     
     
       14. A method of claim 11 wherein said group 8 metal carbonyl is Fe 2  (CO) 9  and said heterobimetallic cluster complex is Cp 2  Mo 2  Fe 2  (μ 3  -S) 4  (CO) 6 . 
     
     
       15. A method of claim 11 wherein said group 8 metal carbonyl is Cp 2  Ni 2  (CO) 2  and said heterobimetallic cluster complex is Cp 4  Mo 2  Ni 2  S 4 . 
     
     
       16. A method of preparing a heterobimetallic cluster complex comprising the steps: (a) reacting Cp 2  Mo 2  (CO) 4  where Cp=η 5  -C 5  H 4  R where R is --CH 3  or --H with Fe 2  S 2  (CO) 6  ; and   (b) recovering a heterobimetallic cluster composition Cp 2  Mo 2  Fe 2  (μ-S) 2  (CO) 8 .